Masks became mandatory in a range of public places in England on Friday, after a long hiatus during which government ministers couldn’t agree on what to do about them. The list of places is explicable but not intuitive: you should wear a mask in shops and supermarkets, and also in takeaways and coffee shops, but not if you are sitting at a table to eat or drink.

A friend runs a bar that also sells records, and explains patiently when people go in that if they’re having a beer, they don’t have to mask up; if they’re buying a record, they do. If they’re drinking a beer while browsing for records, they can remain face-naked until they buy a record, then they have to put a mask on, unless they want another beer. I can easily imagine people going there deliberately to make some kind of mask statement, but then my friend will sell more beer, so what’s the harm?

The sanction is a £100 fine, and nobody wants to police it: not the police, not supermarkets – Sainsbury’s and Asda have already refused. Certainly, without an enforcement army, it’s hard to see how many £100 fines the government will collect, but beyond that, worriers are underestimating the force of a dirty look.

The bigger threat to the success of Project Mask are the inevitable bids to turn it into a badge of political identity, whether by the libertarian right (“masks destroy the economy!”) or the statist left (“wear a mask to signify your belief that the government is failing”). There is no politics here; there is only the one person you might meet, who has to do their job, who would prefer you to wear a mask. It doesn’t matter if they aren’t wearing one. It doesn’t matter if there’s only one of him or her in your entire day, or what the science says, or whether you have read the metastudies. If one person on a till, who has to serve 150 people a day, would prefer you to be masked, that satisfies the basic demands of courtesy, and everything else is noise.

• Zoe Williams is a Guardian columnist